1. Field of the Invention
This invention relates to an electronic circuit element series mounted on a carrier tape, and more particularly to a carrier tape for electronic circuit elements which are adapted to be mounted on printed circuit boards by soldering while being provisionally held on the printed circuit Boards by means of adhesive means.
2. Description of the Prior Art
Generally, mounting of surface-mounted electronic circuit elements on a printed circuit board by soldering is carried out in such a manner that first a predetermined number of electronic circuit elements are provisionally held at predetermined positions on the printed circuit board and then stably fixed together on the printed circuit board by soldering. The provisional or temporary holding of the electronic circuit elements on the printed circuit board which is carried out prior to soldering operation is generally performed by adhesives.
An example of an electronic circuit element series having electronic circuit elements which are adapted to be provisionally held on printed circuit boards through adhesive prior to a soldering operation is found, for example, in Japanese Utility Model Publication No. 11438/1981 (in the name of TDK Corporation). The electronic circuit element series comprises a flat tape extending in a longitudinal direction and having a thermosetting adhesive applied onto one surface thereof, and a plurality of electronic circuit elements held on the surface of the tape through the adhesive. Each of the electronic circuit elements held on the tape, when it is to be mounted on a printed circuit board by, for example, a mounting head of an electronic circuit element mounting apparatus, is adapted to be removed from the tape by means of the mounting head to be provisionally held on the printed circuit board through the adhesive. However, with the conventional electronic circuit element series having the thermosetting adhesive, the thermosetting adhesive is applied onto one surface of the flat tape, so that there is a possibility that dirt and/or dust may directly stick to the adhesive. Also, it is hard to release or extract the electronic circuit elements from the tape by the mounting head because the adhesive adheres to the entire bottom surfaces of the electronic circuit elements to hold them on the tape to a degree sufficient to prevent the smooth peeling-off. Even when an electronic circuit element is released from the tape, it pulls the tape through the adhesive during the peeling-off operation. This results in the tape acting on electronic circuit elements adjacent to the released one when it elastically returns to the original position, thereby causing them to be separated from the tape. Furthermore, there is a possibility that the adhesive may remain on the tape and fail in sticking to an electronic circuit element when the electronic circuit element is peeled off from the tape, so that the electronic circuit element would not be stably provisionally held on the printed circuit board when it is placed on the printed circuit board by the mounting head.
Generally, the electronic circuit element series of the type described above is spirally wound around, for example, a reel for storage and transportation thereof. It is therefore necessary to prevent the electronic circuit elements from being damaged by external force and coming off from the tape when the electronic circuit element series is wound around the reel.